SQL Query Question - getting average without using AVG() function

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SQL-Server-2005

I am looking to get the average value for orders, and average value for order items from the query below. I would like to get the output in this format:
two columns: "Orders Average" and "OrderItems Average") or in one column with each output in its own row. How can I do that? Thank you.

SQL

SELECT (COUNT(Orders.orderid) / SUM(Inventory.price)) AS Orders_Average,
(COUNT(OrderItems.orderid) / SUM(Inventory.price)) AS OrderItems_Average
FROM  ORDERITEMS LEFT OUTER JOIN
               Inventory ON OrderItems.partid = Inventory.partid RIGHT OUTER JOIN
               Orders ON OrderItems.orderid = Orders.orderid

Posted 18-Jan-13 19:09pm

7prince

Updated 19-Jan-13 7:54am

Tharaka MTR

v2

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Sandeep Mewara · Answer 1 · 2013-01-19T09:09:00

Solution 1

Shouldn't the formula be opposite for average calculation? Further, looks like an INNER join should do it for you.

SQL

SELECT 
   (SUM(Inventory.price) / COUNT(Orders.orderid)) AS Orders_Average,
   (SUM(Inventory.price) / COUNT(OrderItems.orderid)) AS OrderItems_Average
FROM  
    ORDERITEMS 
INNER JOIN
     Inventory ON OrderItems.partid = Inventory.partid 
INNER JOIN
     Orders ON OrderItems.orderid = Orders.orderid

Posted 19-Jan-13 9:09am

Sandeep Mewara

Comments

7prince 19-Jan-13 16:11pm

yes. That is right. I switched it to SELECT
(SUM(Inventory.price) / COUNT(Orders.orderid)) AS Orders_Average,
(SUM(Inventory.price) / COUNT(OrderItems.orderid)) AS OrderItems_Average
But inner join doesn't work as it gives the same amount for both averages.

P.S. The number of orders in the ORDERS table is different from the number of orders in the ORDERITEMS table.

so after modifying the query:

SELECT SUM(Inventory.price) / COUNT(Orders.orderid) AS Orders_Average, SUM(Inventory.price) / COUNT(OrderItems.orderid) AS OrderItems_Average

FROM OrderItems LEFT OUTER JOIN
Inventory ON OrderItems.partid = Inventory.partid RIGHT OUTER JOIN
Orders ON OrderItems.orderid = Orders.orderid
it gives slightly differnt averages now. Any feedback if this one is correct or not/ thank you